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<pre><span class="sourceLineNo">001</span>/* ===========================================================<a name="line.1"></a>
<span class="sourceLineNo">002</span> * JFreeChart : a free chart library for the Java(tm) platform<a name="line.2"></a>
<span class="sourceLineNo">003</span> * ===========================================================<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * (C) Copyright 2000-2014, by Object Refinery Limited and Contributors.<a name="line.5"></a>
<span class="sourceLineNo">006</span> *<a name="line.6"></a>
<span class="sourceLineNo">007</span> * Project Info:  http://www.jfree.org/jfreechart/index.html<a name="line.7"></a>
<span class="sourceLineNo">008</span> *<a name="line.8"></a>
<span class="sourceLineNo">009</span> * This library is free software; you can redistribute it and/or modify it<a name="line.9"></a>
<span class="sourceLineNo">010</span> * under the terms of the GNU Lesser General Public License as published by<a name="line.10"></a>
<span class="sourceLineNo">011</span> * the Free Software Foundation; either version 2.1 of the License, or<a name="line.11"></a>
<span class="sourceLineNo">012</span> * (at your option) any later version.<a name="line.12"></a>
<span class="sourceLineNo">013</span> *<a name="line.13"></a>
<span class="sourceLineNo">014</span> * This library is distributed in the hope that it will be useful, but<a name="line.14"></a>
<span class="sourceLineNo">015</span> * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY<a name="line.15"></a>
<span class="sourceLineNo">016</span> * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public<a name="line.16"></a>
<span class="sourceLineNo">017</span> * License for more details.<a name="line.17"></a>
<span class="sourceLineNo">018</span> *<a name="line.18"></a>
<span class="sourceLineNo">019</span> * You should have received a copy of the GNU Lesser General Public<a name="line.19"></a>
<span class="sourceLineNo">020</span> * License along with this library; if not, write to the Free Software<a name="line.20"></a>
<span class="sourceLineNo">021</span> * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,<a name="line.21"></a>
<span class="sourceLineNo">022</span> * USA.<a name="line.22"></a>
<span class="sourceLineNo">023</span> *<a name="line.23"></a>
<span class="sourceLineNo">024</span> * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. <a name="line.24"></a>
<span class="sourceLineNo">025</span> * Other names may be trademarks of their respective owners.]<a name="line.25"></a>
<span class="sourceLineNo">026</span> *<a name="line.26"></a>
<span class="sourceLineNo">027</span> * ---------------<a name="line.27"></a>
<span class="sourceLineNo">028</span> * Statistics.java<a name="line.28"></a>
<span class="sourceLineNo">029</span> * ---------------<a name="line.29"></a>
<span class="sourceLineNo">030</span> * (C) Copyright 2000-2014, by Matthew Wright and Contributors.<a name="line.30"></a>
<span class="sourceLineNo">031</span> *<a name="line.31"></a>
<span class="sourceLineNo">032</span> * Original Author:  Matthew Wright;<a name="line.32"></a>
<span class="sourceLineNo">033</span> * Contributor(s):   David Gilbert (for Object Refinery Limited);<a name="line.33"></a>
<span class="sourceLineNo">034</span> *<a name="line.34"></a>
<span class="sourceLineNo">035</span> * Changes (from 08-Nov-2001)<a name="line.35"></a>
<span class="sourceLineNo">036</span> * --------------------------<a name="line.36"></a>
<span class="sourceLineNo">037</span> * 08-Nov-2001 : Added standard header and tidied Javadoc comments (DG);<a name="line.37"></a>
<span class="sourceLineNo">038</span> *               Moved from JFreeChart to package com.jrefinery.data.* in<a name="line.38"></a>
<span class="sourceLineNo">039</span> *               JCommon class library (DG);<a name="line.39"></a>
<span class="sourceLineNo">040</span> * 24-Jun-2002 : Removed unnecessary local variable (DG);<a name="line.40"></a>
<span class="sourceLineNo">041</span> * 07-Oct-2002 : Fixed errors reported by Checkstyle (DG);<a name="line.41"></a>
<span class="sourceLineNo">042</span> * 26-May-2004 : Moved calculateMean() method from BoxAndWhiskerCalculator (DG);<a name="line.42"></a>
<span class="sourceLineNo">043</span> * 02-Jun-2004 : Fixed bug in calculateMedian() method (DG);<a name="line.43"></a>
<span class="sourceLineNo">044</span> * 11-Jan-2005 : Removed deprecated code in preparation for the 1.0.0<a name="line.44"></a>
<span class="sourceLineNo">045</span> *               release (DG);<a name="line.45"></a>
<span class="sourceLineNo">046</span> * 02-Jul-2013 : Use ParamChecks (DG);<a name="line.46"></a>
<span class="sourceLineNo">047</span> *<a name="line.47"></a>
<span class="sourceLineNo">048</span> */<a name="line.48"></a>
<span class="sourceLineNo">049</span><a name="line.49"></a>
<span class="sourceLineNo">050</span>package org.jfree.data.statistics;<a name="line.50"></a>
<span class="sourceLineNo">051</span><a name="line.51"></a>
<span class="sourceLineNo">052</span>import java.util.ArrayList;<a name="line.52"></a>
<span class="sourceLineNo">053</span>import java.util.Collection;<a name="line.53"></a>
<span class="sourceLineNo">054</span>import java.util.Collections;<a name="line.54"></a>
<span class="sourceLineNo">055</span>import java.util.Iterator;<a name="line.55"></a>
<span class="sourceLineNo">056</span>import java.util.List;<a name="line.56"></a>
<span class="sourceLineNo">057</span>import org.jfree.chart.util.ParamChecks;<a name="line.57"></a>
<span class="sourceLineNo">058</span><a name="line.58"></a>
<span class="sourceLineNo">059</span>/**<a name="line.59"></a>
<span class="sourceLineNo">060</span> * A utility class that provides some common statistical functions.<a name="line.60"></a>
<span class="sourceLineNo">061</span> */<a name="line.61"></a>
<span class="sourceLineNo">062</span>public abstract class Statistics {<a name="line.62"></a>
<span class="sourceLineNo">063</span><a name="line.63"></a>
<span class="sourceLineNo">064</span>    /**<a name="line.64"></a>
<span class="sourceLineNo">065</span>     * Returns the mean of an array of numbers.  This is equivalent to calling<a name="line.65"></a>
<span class="sourceLineNo">066</span>     * {@code calculateMean(values, true)}.<a name="line.66"></a>
<span class="sourceLineNo">067</span>     *<a name="line.67"></a>
<span class="sourceLineNo">068</span>     * @param values  the values ({@code null} not permitted).<a name="line.68"></a>
<span class="sourceLineNo">069</span>     *<a name="line.69"></a>
<span class="sourceLineNo">070</span>     * @return The mean.<a name="line.70"></a>
<span class="sourceLineNo">071</span>     */<a name="line.71"></a>
<span class="sourceLineNo">072</span>    public static double calculateMean(Number[] values) {<a name="line.72"></a>
<span class="sourceLineNo">073</span>        return calculateMean(values, true);<a name="line.73"></a>
<span class="sourceLineNo">074</span>    }<a name="line.74"></a>
<span class="sourceLineNo">075</span><a name="line.75"></a>
<span class="sourceLineNo">076</span>    /**<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * Returns the mean of an array of numbers.<a name="line.77"></a>
<span class="sourceLineNo">078</span>     *<a name="line.78"></a>
<span class="sourceLineNo">079</span>     * @param values  the values ({@code null} not permitted).<a name="line.79"></a>
<span class="sourceLineNo">080</span>     * @param includeNullAndNaN  a flag that controls whether or not<a name="line.80"></a>
<span class="sourceLineNo">081</span>     *     {@code null} and {@code Double.NaN} values are included<a name="line.81"></a>
<span class="sourceLineNo">082</span>     *     in the calculation (if either is present in the array, the result is<a name="line.82"></a>
<span class="sourceLineNo">083</span>     *     {@link Double#NaN}).<a name="line.83"></a>
<span class="sourceLineNo">084</span>     *<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * @return The mean.<a name="line.85"></a>
<span class="sourceLineNo">086</span>     *<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * @since 1.0.3<a name="line.87"></a>
<span class="sourceLineNo">088</span>     */<a name="line.88"></a>
<span class="sourceLineNo">089</span>    public static double calculateMean(Number[] values,<a name="line.89"></a>
<span class="sourceLineNo">090</span>            boolean includeNullAndNaN) {<a name="line.90"></a>
<span class="sourceLineNo">091</span><a name="line.91"></a>
<span class="sourceLineNo">092</span>        ParamChecks.nullNotPermitted(values, "values");<a name="line.92"></a>
<span class="sourceLineNo">093</span>        double sum = 0.0;<a name="line.93"></a>
<span class="sourceLineNo">094</span>        double current;<a name="line.94"></a>
<span class="sourceLineNo">095</span>        int counter = 0;<a name="line.95"></a>
<span class="sourceLineNo">096</span>        for (int i = 0; i &lt; values.length; i++) {<a name="line.96"></a>
<span class="sourceLineNo">097</span>            // treat nulls the same as NaNs<a name="line.97"></a>
<span class="sourceLineNo">098</span>            if (values[i] != null) {<a name="line.98"></a>
<span class="sourceLineNo">099</span>                current = values[i].doubleValue();<a name="line.99"></a>
<span class="sourceLineNo">100</span>            }<a name="line.100"></a>
<span class="sourceLineNo">101</span>            else {<a name="line.101"></a>
<span class="sourceLineNo">102</span>                current = Double.NaN;<a name="line.102"></a>
<span class="sourceLineNo">103</span>            }<a name="line.103"></a>
<span class="sourceLineNo">104</span>            // calculate the sum and count<a name="line.104"></a>
<span class="sourceLineNo">105</span>            if (includeNullAndNaN || !Double.isNaN(current)) {<a name="line.105"></a>
<span class="sourceLineNo">106</span>                sum = sum + current;<a name="line.106"></a>
<span class="sourceLineNo">107</span>                counter++;<a name="line.107"></a>
<span class="sourceLineNo">108</span>            }<a name="line.108"></a>
<span class="sourceLineNo">109</span>        }<a name="line.109"></a>
<span class="sourceLineNo">110</span>        double result = (sum / counter);<a name="line.110"></a>
<span class="sourceLineNo">111</span>        return result;<a name="line.111"></a>
<span class="sourceLineNo">112</span>    }<a name="line.112"></a>
<span class="sourceLineNo">113</span><a name="line.113"></a>
<span class="sourceLineNo">114</span>    /**<a name="line.114"></a>
<span class="sourceLineNo">115</span>     * Returns the mean of a collection of {@code Number} objects.<a name="line.115"></a>
<span class="sourceLineNo">116</span>     *<a name="line.116"></a>
<span class="sourceLineNo">117</span>     * @param values  the values ({@code null} not permitted).<a name="line.117"></a>
<span class="sourceLineNo">118</span>     *<a name="line.118"></a>
<span class="sourceLineNo">119</span>     * @return The mean.<a name="line.119"></a>
<span class="sourceLineNo">120</span>     */<a name="line.120"></a>
<span class="sourceLineNo">121</span>    public static double calculateMean(Collection values) {<a name="line.121"></a>
<span class="sourceLineNo">122</span>        return calculateMean(values, true);<a name="line.122"></a>
<span class="sourceLineNo">123</span>    }<a name="line.123"></a>
<span class="sourceLineNo">124</span><a name="line.124"></a>
<span class="sourceLineNo">125</span>    /**<a name="line.125"></a>
<span class="sourceLineNo">126</span>     * Returns the mean of a collection of {@code Number} objects.<a name="line.126"></a>
<span class="sourceLineNo">127</span>     *<a name="line.127"></a>
<span class="sourceLineNo">128</span>     * @param values  the values ({@code null} not permitted).<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * @param includeNullAndNaN  a flag that controls whether or not<a name="line.129"></a>
<span class="sourceLineNo">130</span>     *     {@code null} and {@code Double.NaN} values are included<a name="line.130"></a>
<span class="sourceLineNo">131</span>     *     in the calculation (if either is present in the array, the result is<a name="line.131"></a>
<span class="sourceLineNo">132</span>     *     {@link Double#NaN}).<a name="line.132"></a>
<span class="sourceLineNo">133</span>     *<a name="line.133"></a>
<span class="sourceLineNo">134</span>     * @return The mean.<a name="line.134"></a>
<span class="sourceLineNo">135</span>     *<a name="line.135"></a>
<span class="sourceLineNo">136</span>     * @since 1.0.3<a name="line.136"></a>
<span class="sourceLineNo">137</span>     */<a name="line.137"></a>
<span class="sourceLineNo">138</span>    public static double calculateMean(Collection values,<a name="line.138"></a>
<span class="sourceLineNo">139</span>            boolean includeNullAndNaN) {<a name="line.139"></a>
<span class="sourceLineNo">140</span><a name="line.140"></a>
<span class="sourceLineNo">141</span>        ParamChecks.nullNotPermitted(values, "values");<a name="line.141"></a>
<span class="sourceLineNo">142</span>        int count = 0;<a name="line.142"></a>
<span class="sourceLineNo">143</span>        double total = 0.0;<a name="line.143"></a>
<span class="sourceLineNo">144</span>        Iterator iterator = values.iterator();<a name="line.144"></a>
<span class="sourceLineNo">145</span>        while (iterator.hasNext()) {<a name="line.145"></a>
<span class="sourceLineNo">146</span>            Object object = iterator.next();<a name="line.146"></a>
<span class="sourceLineNo">147</span>            if (object == null) {<a name="line.147"></a>
<span class="sourceLineNo">148</span>                if (includeNullAndNaN) {<a name="line.148"></a>
<span class="sourceLineNo">149</span>                    return Double.NaN;<a name="line.149"></a>
<span class="sourceLineNo">150</span>                }<a name="line.150"></a>
<span class="sourceLineNo">151</span>            }<a name="line.151"></a>
<span class="sourceLineNo">152</span>            else {<a name="line.152"></a>
<span class="sourceLineNo">153</span>                if (object instanceof Number) {<a name="line.153"></a>
<span class="sourceLineNo">154</span>                    Number number = (Number) object;<a name="line.154"></a>
<span class="sourceLineNo">155</span>                    double value = number.doubleValue();<a name="line.155"></a>
<span class="sourceLineNo">156</span>                    if (Double.isNaN(value)) {<a name="line.156"></a>
<span class="sourceLineNo">157</span>                        if (includeNullAndNaN) {<a name="line.157"></a>
<span class="sourceLineNo">158</span>                            return Double.NaN;<a name="line.158"></a>
<span class="sourceLineNo">159</span>                        }<a name="line.159"></a>
<span class="sourceLineNo">160</span>                    }<a name="line.160"></a>
<span class="sourceLineNo">161</span>                    else {<a name="line.161"></a>
<span class="sourceLineNo">162</span>                        total = total + number.doubleValue();<a name="line.162"></a>
<span class="sourceLineNo">163</span>                        count = count + 1;<a name="line.163"></a>
<span class="sourceLineNo">164</span>                    }<a name="line.164"></a>
<span class="sourceLineNo">165</span>                }<a name="line.165"></a>
<span class="sourceLineNo">166</span>            }<a name="line.166"></a>
<span class="sourceLineNo">167</span>        }<a name="line.167"></a>
<span class="sourceLineNo">168</span>        return total / count;<a name="line.168"></a>
<span class="sourceLineNo">169</span>    }<a name="line.169"></a>
<span class="sourceLineNo">170</span><a name="line.170"></a>
<span class="sourceLineNo">171</span>    /**<a name="line.171"></a>
<span class="sourceLineNo">172</span>     * Calculates the median for a list of values ({@code Number} objects).<a name="line.172"></a>
<span class="sourceLineNo">173</span>     * The list of values will be copied, and the copy sorted, before<a name="line.173"></a>
<span class="sourceLineNo">174</span>     * calculating the median.  To avoid this step (if your list of values<a name="line.174"></a>
<span class="sourceLineNo">175</span>     * is already sorted), use the {@link #calculateMedian(List, boolean)}<a name="line.175"></a>
<span class="sourceLineNo">176</span>     * method.<a name="line.176"></a>
<span class="sourceLineNo">177</span>     *<a name="line.177"></a>
<span class="sourceLineNo">178</span>     * @param values  the values ({@code null} permitted).<a name="line.178"></a>
<span class="sourceLineNo">179</span>     *<a name="line.179"></a>
<span class="sourceLineNo">180</span>     * @return The median.<a name="line.180"></a>
<span class="sourceLineNo">181</span>     */<a name="line.181"></a>
<span class="sourceLineNo">182</span>    public static double calculateMedian(List values) {<a name="line.182"></a>
<span class="sourceLineNo">183</span>        return calculateMedian(values, true);<a name="line.183"></a>
<span class="sourceLineNo">184</span>    }<a name="line.184"></a>
<span class="sourceLineNo">185</span><a name="line.185"></a>
<span class="sourceLineNo">186</span>    /**<a name="line.186"></a>
<span class="sourceLineNo">187</span>     * Calculates the median for a list of values ({@code Number} objects).<a name="line.187"></a>
<span class="sourceLineNo">188</span>     * If {@code copyAndSort} is {@code false}, the list is assumed<a name="line.188"></a>
<span class="sourceLineNo">189</span>     * to be presorted in ascending order by value.<a name="line.189"></a>
<span class="sourceLineNo">190</span>     *<a name="line.190"></a>
<span class="sourceLineNo">191</span>     * @param values  the values ({@code null} permitted).<a name="line.191"></a>
<span class="sourceLineNo">192</span>     * @param copyAndSort  a flag that controls whether the list of values is<a name="line.192"></a>
<span class="sourceLineNo">193</span>     *                     copied and sorted.<a name="line.193"></a>
<span class="sourceLineNo">194</span>     *<a name="line.194"></a>
<span class="sourceLineNo">195</span>     * @return The median.<a name="line.195"></a>
<span class="sourceLineNo">196</span>     */<a name="line.196"></a>
<span class="sourceLineNo">197</span>    public static double calculateMedian(List values, boolean copyAndSort) {<a name="line.197"></a>
<span class="sourceLineNo">198</span><a name="line.198"></a>
<span class="sourceLineNo">199</span>        double result = Double.NaN;<a name="line.199"></a>
<span class="sourceLineNo">200</span>        if (values != null) {<a name="line.200"></a>
<span class="sourceLineNo">201</span>            if (copyAndSort) {<a name="line.201"></a>
<span class="sourceLineNo">202</span>                int itemCount = values.size();<a name="line.202"></a>
<span class="sourceLineNo">203</span>                List copy = new ArrayList(itemCount);<a name="line.203"></a>
<span class="sourceLineNo">204</span>                for (int i = 0; i &lt; itemCount; i++) {<a name="line.204"></a>
<span class="sourceLineNo">205</span>                    copy.add(i, values.get(i));<a name="line.205"></a>
<span class="sourceLineNo">206</span>                }<a name="line.206"></a>
<span class="sourceLineNo">207</span>                Collections.sort(copy);<a name="line.207"></a>
<span class="sourceLineNo">208</span>                values = copy;<a name="line.208"></a>
<span class="sourceLineNo">209</span>            }<a name="line.209"></a>
<span class="sourceLineNo">210</span>            int count = values.size();<a name="line.210"></a>
<span class="sourceLineNo">211</span>            if (count &gt; 0) {<a name="line.211"></a>
<span class="sourceLineNo">212</span>                if (count % 2 == 1) {<a name="line.212"></a>
<span class="sourceLineNo">213</span>                    if (count &gt; 1) {<a name="line.213"></a>
<span class="sourceLineNo">214</span>                        Number value = (Number) values.get((count - 1) / 2);<a name="line.214"></a>
<span class="sourceLineNo">215</span>                        result = value.doubleValue();<a name="line.215"></a>
<span class="sourceLineNo">216</span>                    }<a name="line.216"></a>
<span class="sourceLineNo">217</span>                    else {<a name="line.217"></a>
<span class="sourceLineNo">218</span>                        Number value = (Number) values.get(0);<a name="line.218"></a>
<span class="sourceLineNo">219</span>                        result = value.doubleValue();<a name="line.219"></a>
<span class="sourceLineNo">220</span>                    }<a name="line.220"></a>
<span class="sourceLineNo">221</span>                }<a name="line.221"></a>
<span class="sourceLineNo">222</span>                else {<a name="line.222"></a>
<span class="sourceLineNo">223</span>                    Number value1 = (Number) values.get(count / 2 - 1);<a name="line.223"></a>
<span class="sourceLineNo">224</span>                    Number value2 = (Number) values.get(count / 2);<a name="line.224"></a>
<span class="sourceLineNo">225</span>                    result = (value1.doubleValue() + value2.doubleValue())<a name="line.225"></a>
<span class="sourceLineNo">226</span>                             / 2.0;<a name="line.226"></a>
<span class="sourceLineNo">227</span>                }<a name="line.227"></a>
<span class="sourceLineNo">228</span>            }<a name="line.228"></a>
<span class="sourceLineNo">229</span>        }<a name="line.229"></a>
<span class="sourceLineNo">230</span>        return result;<a name="line.230"></a>
<span class="sourceLineNo">231</span>    }<a name="line.231"></a>
<span class="sourceLineNo">232</span><a name="line.232"></a>
<span class="sourceLineNo">233</span>    /**<a name="line.233"></a>
<span class="sourceLineNo">234</span>     * Calculates the median for a sublist within a list of values<a name="line.234"></a>
<span class="sourceLineNo">235</span>     * ({@code Number} objects).<a name="line.235"></a>
<span class="sourceLineNo">236</span>     *<a name="line.236"></a>
<span class="sourceLineNo">237</span>     * @param values  the values, in any order ({@code null} not permitted).<a name="line.237"></a>
<span class="sourceLineNo">238</span>     * @param start  the start index.<a name="line.238"></a>
<span class="sourceLineNo">239</span>     * @param end  the end index.<a name="line.239"></a>
<span class="sourceLineNo">240</span>     *<a name="line.240"></a>
<span class="sourceLineNo">241</span>     * @return The median.<a name="line.241"></a>
<span class="sourceLineNo">242</span>     */<a name="line.242"></a>
<span class="sourceLineNo">243</span>    public static double calculateMedian(List values, int start, int end) {<a name="line.243"></a>
<span class="sourceLineNo">244</span>        return calculateMedian(values, start, end, true);<a name="line.244"></a>
<span class="sourceLineNo">245</span>    }<a name="line.245"></a>
<span class="sourceLineNo">246</span><a name="line.246"></a>
<span class="sourceLineNo">247</span>    /**<a name="line.247"></a>
<span class="sourceLineNo">248</span>     * Calculates the median for a sublist within a list of values<a name="line.248"></a>
<span class="sourceLineNo">249</span>     * ({@code Number} objects).  The entire list will be sorted if the<a name="line.249"></a>
<span class="sourceLineNo">250</span>     * {@code ascending} argument is {@code false}.<a name="line.250"></a>
<span class="sourceLineNo">251</span>     *<a name="line.251"></a>
<span class="sourceLineNo">252</span>     * @param values  the values ({@code null} not permitted).<a name="line.252"></a>
<span class="sourceLineNo">253</span>     * @param start  the start index.<a name="line.253"></a>
<span class="sourceLineNo">254</span>     * @param end  the end index.<a name="line.254"></a>
<span class="sourceLineNo">255</span>     * @param copyAndSort  a flag that that controls whether the list of values<a name="line.255"></a>
<span class="sourceLineNo">256</span>     *                     is copied and sorted.<a name="line.256"></a>
<span class="sourceLineNo">257</span>     *<a name="line.257"></a>
<span class="sourceLineNo">258</span>     * @return The median.<a name="line.258"></a>
<span class="sourceLineNo">259</span>     */<a name="line.259"></a>
<span class="sourceLineNo">260</span>    public static double calculateMedian(List values, int start, int end,<a name="line.260"></a>
<span class="sourceLineNo">261</span>                                         boolean copyAndSort) {<a name="line.261"></a>
<span class="sourceLineNo">262</span><a name="line.262"></a>
<span class="sourceLineNo">263</span>        double result = Double.NaN;<a name="line.263"></a>
<span class="sourceLineNo">264</span>        if (copyAndSort) {<a name="line.264"></a>
<span class="sourceLineNo">265</span>            List working = new ArrayList(end - start + 1);<a name="line.265"></a>
<span class="sourceLineNo">266</span>            for (int i = start; i &lt;= end; i++) {<a name="line.266"></a>
<span class="sourceLineNo">267</span>                working.add(values.get(i));<a name="line.267"></a>
<span class="sourceLineNo">268</span>            }<a name="line.268"></a>
<span class="sourceLineNo">269</span>            Collections.sort(working);<a name="line.269"></a>
<span class="sourceLineNo">270</span>            result = calculateMedian(working, false);<a name="line.270"></a>
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<span class="sourceLineNo">273</span>            int count = end - start + 1;<a name="line.273"></a>
<span class="sourceLineNo">274</span>            if (count &gt; 0) {<a name="line.274"></a>
<span class="sourceLineNo">275</span>                if (count % 2 == 1) {<a name="line.275"></a>
<span class="sourceLineNo">276</span>                    if (count &gt; 1) {<a name="line.276"></a>
<span class="sourceLineNo">277</span>                        Number value<a name="line.277"></a>
<span class="sourceLineNo">278</span>                            = (Number) values.get(start + (count - 1) / 2);<a name="line.278"></a>
<span class="sourceLineNo">279</span>                        result = value.doubleValue();<a name="line.279"></a>
<span class="sourceLineNo">280</span>                    }<a name="line.280"></a>
<span class="sourceLineNo">281</span>                    else {<a name="line.281"></a>
<span class="sourceLineNo">282</span>                        Number value = (Number) values.get(start);<a name="line.282"></a>
<span class="sourceLineNo">283</span>                        result = value.doubleValue();<a name="line.283"></a>
<span class="sourceLineNo">284</span>                    }<a name="line.284"></a>
<span class="sourceLineNo">285</span>                }<a name="line.285"></a>
<span class="sourceLineNo">286</span>                else {<a name="line.286"></a>
<span class="sourceLineNo">287</span>                    Number value1 = (Number) values.get(start + count / 2 - 1);<a name="line.287"></a>
<span class="sourceLineNo">288</span>                    Number value2 = (Number) values.get(start + count / 2);<a name="line.288"></a>
<span class="sourceLineNo">289</span>                    result<a name="line.289"></a>
<span class="sourceLineNo">290</span>                        = (value1.doubleValue() + value2.doubleValue()) / 2.0;<a name="line.290"></a>
<span class="sourceLineNo">291</span>                }<a name="line.291"></a>
<span class="sourceLineNo">292</span>            }<a name="line.292"></a>
<span class="sourceLineNo">293</span>        }<a name="line.293"></a>
<span class="sourceLineNo">294</span>        return result;<a name="line.294"></a>
<span class="sourceLineNo">295</span><a name="line.295"></a>
<span class="sourceLineNo">296</span>    }<a name="line.296"></a>
<span class="sourceLineNo">297</span><a name="line.297"></a>
<span class="sourceLineNo">298</span>    /**<a name="line.298"></a>
<span class="sourceLineNo">299</span>     * Returns the standard deviation of a set of numbers.<a name="line.299"></a>
<span class="sourceLineNo">300</span>     *<a name="line.300"></a>
<span class="sourceLineNo">301</span>     * @param data  the data ({@code null} or zero length array not<a name="line.301"></a>
<span class="sourceLineNo">302</span>     *     permitted).<a name="line.302"></a>
<span class="sourceLineNo">303</span>     *<a name="line.303"></a>
<span class="sourceLineNo">304</span>     * @return The standard deviation of a set of numbers.<a name="line.304"></a>
<span class="sourceLineNo">305</span>     */<a name="line.305"></a>
<span class="sourceLineNo">306</span>    public static double getStdDev(Number[] data) {<a name="line.306"></a>
<span class="sourceLineNo">307</span>        ParamChecks.nullNotPermitted(data, "data");<a name="line.307"></a>
<span class="sourceLineNo">308</span>        if (data.length == 0) {<a name="line.308"></a>
<span class="sourceLineNo">309</span>            throw new IllegalArgumentException("Zero length 'data' array.");<a name="line.309"></a>
<span class="sourceLineNo">310</span>        }<a name="line.310"></a>
<span class="sourceLineNo">311</span>        double avg = calculateMean(data);<a name="line.311"></a>
<span class="sourceLineNo">312</span>        double sum = 0.0;<a name="line.312"></a>
<span class="sourceLineNo">313</span><a name="line.313"></a>
<span class="sourceLineNo">314</span>        for (int counter = 0; counter &lt; data.length; counter++) {<a name="line.314"></a>
<span class="sourceLineNo">315</span>            double diff = data[counter].doubleValue() - avg;<a name="line.315"></a>
<span class="sourceLineNo">316</span>            sum = sum + diff * diff;<a name="line.316"></a>
<span class="sourceLineNo">317</span>        }<a name="line.317"></a>
<span class="sourceLineNo">318</span>        return Math.sqrt(sum / (data.length - 1));<a name="line.318"></a>
<span class="sourceLineNo">319</span>    }<a name="line.319"></a>
<span class="sourceLineNo">320</span><a name="line.320"></a>
<span class="sourceLineNo">321</span>    /**<a name="line.321"></a>
<span class="sourceLineNo">322</span>     * Fits a straight line to a set of (x, y) data, returning the slope and<a name="line.322"></a>
<span class="sourceLineNo">323</span>     * intercept.<a name="line.323"></a>
<span class="sourceLineNo">324</span>     *<a name="line.324"></a>
<span class="sourceLineNo">325</span>     * @param xData  the x-data ({@code null} not permitted).<a name="line.325"></a>
<span class="sourceLineNo">326</span>     * @param yData  the y-data ({@code null} not permitted).<a name="line.326"></a>
<span class="sourceLineNo">327</span>     *<a name="line.327"></a>
<span class="sourceLineNo">328</span>     * @return A double array with the intercept in [0] and the slope in [1].<a name="line.328"></a>
<span class="sourceLineNo">329</span>     */<a name="line.329"></a>
<span class="sourceLineNo">330</span>    public static double[] getLinearFit(Number[] xData, Number[] yData) {<a name="line.330"></a>
<span class="sourceLineNo">331</span><a name="line.331"></a>
<span class="sourceLineNo">332</span>        ParamChecks.nullNotPermitted(xData, "xData");<a name="line.332"></a>
<span class="sourceLineNo">333</span>        ParamChecks.nullNotPermitted(yData, "yData");<a name="line.333"></a>
<span class="sourceLineNo">334</span>        if (xData.length != yData.length) {<a name="line.334"></a>
<span class="sourceLineNo">335</span>            throw new IllegalArgumentException(<a name="line.335"></a>
<span class="sourceLineNo">336</span>                "Statistics.getLinearFit(): array lengths must be equal.");<a name="line.336"></a>
<span class="sourceLineNo">337</span>        }<a name="line.337"></a>
<span class="sourceLineNo">338</span><a name="line.338"></a>
<span class="sourceLineNo">339</span>        double[] result = new double[2];<a name="line.339"></a>
<span class="sourceLineNo">340</span>        // slope<a name="line.340"></a>
<span class="sourceLineNo">341</span>        result[1] = getSlope(xData, yData);<a name="line.341"></a>
<span class="sourceLineNo">342</span>        // intercept<a name="line.342"></a>
<span class="sourceLineNo">343</span>        result[0] = calculateMean(yData) - result[1] * calculateMean(xData);<a name="line.343"></a>
<span class="sourceLineNo">344</span><a name="line.344"></a>
<span class="sourceLineNo">345</span>        return result;<a name="line.345"></a>
<span class="sourceLineNo">346</span><a name="line.346"></a>
<span class="sourceLineNo">347</span>    }<a name="line.347"></a>
<span class="sourceLineNo">348</span><a name="line.348"></a>
<span class="sourceLineNo">349</span>    /**<a name="line.349"></a>
<span class="sourceLineNo">350</span>     * Finds the slope of a regression line using least squares.<a name="line.350"></a>
<span class="sourceLineNo">351</span>     *<a name="line.351"></a>
<span class="sourceLineNo">352</span>     * @param xData  the x-values ({@code null} not permitted).<a name="line.352"></a>
<span class="sourceLineNo">353</span>     * @param yData  the y-values ({@code null} not permitted).<a name="line.353"></a>
<span class="sourceLineNo">354</span>     *<a name="line.354"></a>
<span class="sourceLineNo">355</span>     * @return The slope.<a name="line.355"></a>
<span class="sourceLineNo">356</span>     */<a name="line.356"></a>
<span class="sourceLineNo">357</span>    public static double getSlope(Number[] xData, Number[] yData) {<a name="line.357"></a>
<span class="sourceLineNo">358</span>        ParamChecks.nullNotPermitted(xData, "xData");<a name="line.358"></a>
<span class="sourceLineNo">359</span>        ParamChecks.nullNotPermitted(yData, "yData");<a name="line.359"></a>
<span class="sourceLineNo">360</span>        if (xData.length != yData.length) {<a name="line.360"></a>
<span class="sourceLineNo">361</span>            throw new IllegalArgumentException("Array lengths must be equal.");<a name="line.361"></a>
<span class="sourceLineNo">362</span>        }<a name="line.362"></a>
<span class="sourceLineNo">363</span><a name="line.363"></a>
<span class="sourceLineNo">364</span>        // ********* stat function for linear slope ********<a name="line.364"></a>
<span class="sourceLineNo">365</span>        // y = a + bx<a name="line.365"></a>
<span class="sourceLineNo">366</span>        // a = ybar - b * xbar<a name="line.366"></a>
<span class="sourceLineNo">367</span>        //     sum(x * y) - (sum (x) * sum(y)) / n<a name="line.367"></a>
<span class="sourceLineNo">368</span>        // b = ------------------------------------<a name="line.368"></a>
<span class="sourceLineNo">369</span>        //     sum (x^2) - (sum(x)^2 / n<a name="line.369"></a>
<span class="sourceLineNo">370</span>        // *************************************************<a name="line.370"></a>
<span class="sourceLineNo">371</span><a name="line.371"></a>
<span class="sourceLineNo">372</span>        // sum of x, x^2, x * y, y<a name="line.372"></a>
<span class="sourceLineNo">373</span>        double sx = 0.0, sxx = 0.0, sxy = 0.0, sy = 0.0;<a name="line.373"></a>
<span class="sourceLineNo">374</span>        int counter;<a name="line.374"></a>
<span class="sourceLineNo">375</span>        for (counter = 0; counter &lt; xData.length; counter++) {<a name="line.375"></a>
<span class="sourceLineNo">376</span>            sx = sx + xData[counter].doubleValue();<a name="line.376"></a>
<span class="sourceLineNo">377</span>            sxx = sxx + Math.pow(xData[counter].doubleValue(), 2);<a name="line.377"></a>
<span class="sourceLineNo">378</span>            sxy = sxy + yData[counter].doubleValue()<a name="line.378"></a>
<span class="sourceLineNo">379</span>                      * xData[counter].doubleValue();<a name="line.379"></a>
<span class="sourceLineNo">380</span>            sy = sy + yData[counter].doubleValue();<a name="line.380"></a>
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<span class="sourceLineNo">382</span>        return (sxy - (sx * sy) / counter) / (sxx - (sx * sx) / counter);<a name="line.382"></a>
<span class="sourceLineNo">383</span><a name="line.383"></a>
<span class="sourceLineNo">384</span>    }<a name="line.384"></a>
<span class="sourceLineNo">385</span><a name="line.385"></a>
<span class="sourceLineNo">386</span>    /**<a name="line.386"></a>
<span class="sourceLineNo">387</span>     * Calculates the correlation between two datasets.  Both arrays should<a name="line.387"></a>
<span class="sourceLineNo">388</span>     * contain the same number of items.  Null values are treated as zero.<a name="line.388"></a>
<span class="sourceLineNo">389</span>     * &lt;P&gt;<a name="line.389"></a>
<span class="sourceLineNo">390</span>     * Information about the correlation calculation was obtained from:<a name="line.390"></a>
<span class="sourceLineNo">391</span>     *<a name="line.391"></a>
<span class="sourceLineNo">392</span>     * http://trochim.human.cornell.edu/kb/statcorr.htm<a name="line.392"></a>
<span class="sourceLineNo">393</span>     *<a name="line.393"></a>
<span class="sourceLineNo">394</span>     * @param data1  the first dataset.<a name="line.394"></a>
<span class="sourceLineNo">395</span>     * @param data2  the second dataset.<a name="line.395"></a>
<span class="sourceLineNo">396</span>     *<a name="line.396"></a>
<span class="sourceLineNo">397</span>     * @return The correlation.<a name="line.397"></a>
<span class="sourceLineNo">398</span>     */<a name="line.398"></a>
<span class="sourceLineNo">399</span>    public static double getCorrelation(Number[] data1, Number[] data2) {<a name="line.399"></a>
<span class="sourceLineNo">400</span>        ParamChecks.nullNotPermitted(data1, "data1");<a name="line.400"></a>
<span class="sourceLineNo">401</span>        ParamChecks.nullNotPermitted(data2, "data2");<a name="line.401"></a>
<span class="sourceLineNo">402</span>        if (data1.length != data2.length) {<a name="line.402"></a>
<span class="sourceLineNo">403</span>            throw new IllegalArgumentException(<a name="line.403"></a>
<span class="sourceLineNo">404</span>                "'data1' and 'data2' arrays must have same length."<a name="line.404"></a>
<span class="sourceLineNo">405</span>            );<a name="line.405"></a>
<span class="sourceLineNo">406</span>        }<a name="line.406"></a>
<span class="sourceLineNo">407</span>        int n = data1.length;<a name="line.407"></a>
<span class="sourceLineNo">408</span>        double sumX = 0.0;<a name="line.408"></a>
<span class="sourceLineNo">409</span>        double sumY = 0.0;<a name="line.409"></a>
<span class="sourceLineNo">410</span>        double sumX2 = 0.0;<a name="line.410"></a>
<span class="sourceLineNo">411</span>        double sumY2 = 0.0;<a name="line.411"></a>
<span class="sourceLineNo">412</span>        double sumXY = 0.0;<a name="line.412"></a>
<span class="sourceLineNo">413</span>        for (int i = 0; i &lt; n; i++) {<a name="line.413"></a>
<span class="sourceLineNo">414</span>            double x = 0.0;<a name="line.414"></a>
<span class="sourceLineNo">415</span>            if (data1[i] != null) {<a name="line.415"></a>
<span class="sourceLineNo">416</span>                x = data1[i].doubleValue();<a name="line.416"></a>
<span class="sourceLineNo">417</span>            }<a name="line.417"></a>
<span class="sourceLineNo">418</span>            double y = 0.0;<a name="line.418"></a>
<span class="sourceLineNo">419</span>            if (data2[i] != null) {<a name="line.419"></a>
<span class="sourceLineNo">420</span>                y = data2[i].doubleValue();<a name="line.420"></a>
<span class="sourceLineNo">421</span>            }<a name="line.421"></a>
<span class="sourceLineNo">422</span>            sumX = sumX + x;<a name="line.422"></a>
<span class="sourceLineNo">423</span>            sumY = sumY + y;<a name="line.423"></a>
<span class="sourceLineNo">424</span>            sumXY = sumXY + (x * y);<a name="line.424"></a>
<span class="sourceLineNo">425</span>            sumX2 = sumX2 + (x * x);<a name="line.425"></a>
<span class="sourceLineNo">426</span>            sumY2 = sumY2 + (y * y);<a name="line.426"></a>
<span class="sourceLineNo">427</span>        }<a name="line.427"></a>
<span class="sourceLineNo">428</span>        return (n * sumXY - sumX * sumY) / Math.pow((n * sumX2 - sumX * sumX)<a name="line.428"></a>
<span class="sourceLineNo">429</span>                * (n * sumY2 - sumY * sumY), 0.5);<a name="line.429"></a>
<span class="sourceLineNo">430</span>    }<a name="line.430"></a>
<span class="sourceLineNo">431</span><a name="line.431"></a>
<span class="sourceLineNo">432</span>    /**<a name="line.432"></a>
<span class="sourceLineNo">433</span>     * Returns a data set for a moving average on the data set passed in.<a name="line.433"></a>
<span class="sourceLineNo">434</span>     *<a name="line.434"></a>
<span class="sourceLineNo">435</span>     * @param xData  an array of the x data.<a name="line.435"></a>
<span class="sourceLineNo">436</span>     * @param yData  an array of the y data.<a name="line.436"></a>
<span class="sourceLineNo">437</span>     * @param period  the number of data points to average<a name="line.437"></a>
<span class="sourceLineNo">438</span>     *<a name="line.438"></a>
<span class="sourceLineNo">439</span>     * @return A double[][] the length of the data set in the first dimension,<a name="line.439"></a>
<span class="sourceLineNo">440</span>     *         with two doubles for x and y in the second dimension<a name="line.440"></a>
<span class="sourceLineNo">441</span>     */<a name="line.441"></a>
<span class="sourceLineNo">442</span>    public static double[][] getMovingAverage(Number[] xData, Number[] yData,<a name="line.442"></a>
<span class="sourceLineNo">443</span>            int period) {<a name="line.443"></a>
<span class="sourceLineNo">444</span><a name="line.444"></a>
<span class="sourceLineNo">445</span>        // check arguments...<a name="line.445"></a>
<span class="sourceLineNo">446</span>        if (xData.length != yData.length) {<a name="line.446"></a>
<span class="sourceLineNo">447</span>            throw new IllegalArgumentException("Array lengths must be equal.");<a name="line.447"></a>
<span class="sourceLineNo">448</span>        }<a name="line.448"></a>
<span class="sourceLineNo">449</span><a name="line.449"></a>
<span class="sourceLineNo">450</span>        if (period &gt; xData.length) {<a name="line.450"></a>
<span class="sourceLineNo">451</span>            throw new IllegalArgumentException(<a name="line.451"></a>
<span class="sourceLineNo">452</span>                "Period can't be longer than dataset.");<a name="line.452"></a>
<span class="sourceLineNo">453</span>        }<a name="line.453"></a>
<span class="sourceLineNo">454</span><a name="line.454"></a>
<span class="sourceLineNo">455</span>        double[][] result = new double[xData.length - period][2];<a name="line.455"></a>
<span class="sourceLineNo">456</span>        for (int i = 0; i &lt; result.length; i++) {<a name="line.456"></a>
<span class="sourceLineNo">457</span>            result[i][0] = xData[i + period].doubleValue();<a name="line.457"></a>
<span class="sourceLineNo">458</span>            // holds the moving average sum<a name="line.458"></a>
<span class="sourceLineNo">459</span>            double sum = 0.0;<a name="line.459"></a>
<span class="sourceLineNo">460</span>            for (int j = 0; j &lt; period; j++) {<a name="line.460"></a>
<span class="sourceLineNo">461</span>                sum += yData[i + j].doubleValue();<a name="line.461"></a>
<span class="sourceLineNo">462</span>            }<a name="line.462"></a>
<span class="sourceLineNo">463</span>            sum = sum / period;<a name="line.463"></a>
<span class="sourceLineNo">464</span>            result[i][1] = sum;<a name="line.464"></a>
<span class="sourceLineNo">465</span>        }<a name="line.465"></a>
<span class="sourceLineNo">466</span>        return result;<a name="line.466"></a>
<span class="sourceLineNo">467</span><a name="line.467"></a>
<span class="sourceLineNo">468</span>    }<a name="line.468"></a>
<span class="sourceLineNo">469</span><a name="line.469"></a>
<span class="sourceLineNo">470</span>}<a name="line.470"></a>




























































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